1. Field of Invention
This invention relates to an improved radiant heating unit and to an improved method of operation thereof. More particularly, this invention relates to a gas powered radiant heating unit that can be used with roadway surface reconditioning machines to heat various surfaces, including asphalt over a relatively large area.
2. Description of the Prior Art
It is known to have radiant heating units for use in repairing asphalt roadway surfaces. The units can be used with a scarifier or patcher. Most units are powered by low pressure propane gas. A radiant heating unit is described in U.S. Pat. No. 5,218,952 issued to Neufeldt on Jun. 15, 1993. The Neufeldt patent describes a radiant heating unit having a housing with a layer of ceramic fiber sandwiched between two layers of mesh. The heating unit described in the Neufeldt patent works well and is designed to withstand rough treatment. However, due to the extreme temperature conditions under which the heating unit operates, the mesh can fail or the ceramic fiber can become damaged. When this occurs, the housing portion of the unit must be returned to the manufacturer for refurbishing. The manufacturer then removes the old layers and replaces them with a new layer of ceramic fiber sandwiched between two new layers of mesh. This procedure takes approximately five to six hours for the manufacturer to complete, but the downtime for the unit to the user can easily be one to two weeks.
It is an object of the present invention to improve the heating unit described in U.S. Pat. No. 5,218,952 by allowing the unit to be repaired quickly on site, thereby virtually eliminating nearly all of the downtime required for the previous device. It is a further object of the present invention to provide a cartridge that is quickly and easily removable and replaceable within the unit on site, the cartridge including the layer of ceramic fibre.
A radiant heating unit has supply means for supplying a quantity of fuel in vapor form at a predetermined pressure. There are means to mix air into the fuel and a housing having a periphery surrounding an open bottom. A removable and replaceable cartridge is affixed to the periphery, the cartridge covering the open bottom with a skirt extending downward beyond the cartridge. The housing and the cartridge define a chamber and the cartridge separates the chamber from ambient air. The chamber is connected to receive a fuel/air mixture. The cartridge is removable and replaceable in the housing and contains multiple layers of non-flammable materials that are bound together into a single component. The layers are porous enough to allow the fuel/air mixture to flow through the cartridge at a rate so that combustion occurs at an outer surface of the cartridge.
A method of operating a radiant heating unit having a housing with an open bottom and a cartridge covering the open bottom with a skirt extending downward from the cartridge, the cartridge being sandwiched between the housing and skirt by retainers, the cartridge and housing defining a chamber, said method comprising the steps of commencing with a cartridge installed in the unit, when the cartridge becomes worn, removing the cartridge from the housing on site by removing the retainers, separating the skirt from the cartridge, and replacing the cartridge with a replacement cartridge and attaching the skirt to the housing with the cartridge sandwiched in between by reattaching the retainers.